Born in 1832 in Edo as the eldest son of the shogunal retainer Nakamura Buhei. His childhood name was Sensaburo, and his pen name Keiu. He studied Confucianism at the Shoheizaka Gakumonjo and later took up Dutch and English studies. In 1866 he went to England as overseer of the shogunate's students in Britain, and studied in London for two years. After returning, he translated Samuel Smiles' Self-Help and published it in 1871 as 'Saikoku Risshihen.' Its opening, 'Heaven helps those who help themselves,' imprinted itself on the young men of Meiji, and the work became an unprecedented bestseller, selling over a million copies from the late Tokugawa period into Meiji. Around the same time he also translated J. S. Mill's On Liberty as 'Jiyu no Kotowari,' introducing Western liberalism to Japan. In 1873 he opened the private school 'Dojinsha,' which developed alongside Fukuzawa Yukichi's Keio Gijuku as one of the leading private schools of early Meiji. In 1874, together with Mori Arinori and Nishi Amane, he formed the Meirokusha society and ran an enlightenment campaign in its Meiroku Zasshi. In 1881 he became professor of ethics at Tokyo University. He converted to Christianity and worked actively for women's education. He died in 1891 at age 60.

A tolerant thinker who, having started out as a Confucian scholar, flexibly embraced Christianity and Western liberalism. Of noble character, he was called 'the Socrates of the East' and educated the students of Dojinsha through sheer force of virtue. Poor in political ambition, he gave his life to scholarship, translation, and education. Zealous also for the education of the weak — women, commoners, prisoners — he is a figure representative of the conscience of the Meiji enlightenment.

'Saikoku Risshihen' planted the ideal of 'rising in the world' in the young men of Meiji and became a spiritual foundation for capitalist Japan. The phrase he rendered, 'Heaven helps those who help themselves,' is still famous to the Japanese people today. Dojinsha produced many Meiji intellectuals and laid a foundation of private-school education alongside Fukuzawa's Keio and Okuma's Waseda. The Meirokusha, through Meiroku Zasshi, created the intellectual discursive space of modern Japan and became the starting point of 'enlightenment' in the country.